請用此 Handle URI 來引用此文件:
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/60839
標題: | 探討磷脂質絲胺酸翻轉酶調控第一腺嘌呤核苷三磷酸核醣化因子相似蛋白之三磷酸鳥糞嘌呤水解過程 Mechanism of flippase Drs2p in modulating GTP hydrolysis of Arl1p |
作者: | Zzu-Jung Chen 陳思蓉 |
指導教授: | 李芳仁(Fang-Jen Lee) |
關鍵字: | 第一腺嘌呤核?三磷酸核醣化因子相似蛋白,磷脂質絲胺酸翻轉?三磷酸鳥糞嘌呤水解, Arl1,Drs2,GTPase, |
出版年 : | 2013 |
學位: | 碩士 |
摘要: | 磷脂質絲胺酸翻轉酶(Drs2p)為一類P型三磷酸腺酶,位於高機氏體上具有翻轉磷脂質絲胺酸的能力,且在酵母菌中參與許多蛋白質運輸過程;第一腺嘌呤核苷二磷酸核醣化因子相似蛋白(Arl1p)也被知曉調控許多囊泡運輸過程。近期已被證實,Arl1p會與一鳥糞嘌呤核苷三磷酸交換蛋白(GEF),Gea2p,及Drs2p形成複合體,且共同調控Drs2p在高基氏體上翻轉磷脂質絲胺酸的能力;且已被報導Arl1p的反應蛋白之一,Imh1p,為一高基氏蛋白,會與Arl1p形成複合四聚體並衰減其活化蛋白(GAP),Gcs1p,去活化Arl1p-GTP的能力。出乎意料地,在drs2D的細胞中Imh1p是無法位在高基氏體上,但Arl1p這時仍位於順式高基氏體網絡(TGN);Drs2p調控鳥糞嘌呤核苷三磷酸(GTP)水解過程仍未被研究,而在此篇中我們證明Drs2p調控Arl1p的GTP水解過程是藉由干擾其活化因子Gcs1p靠近Arl1p的能力;首先在drs2D的細胞中Arl1p仍位於TGN上,而在提高其活化因子Gcs1p表現量後,野生型細胞中的GTP水解即被增加,但drs2D細胞則否。其次,在缺乏Drs2p時,Gcs1p在磷脂膜上的比例即會下降,也影響到Gcs1p位於TGN的比例。因此,本篇論文證實Drs2p藉由調控Arl1p-GTP水解過程是藉由控制磷脂膜曲度形成而影響到Gcs1p接近及活化Arl1p的能力。 Drs2p, a resident type 4 P-type ATPase (P4-ATPase), is required for the phosphatidylserine (PS) flippase activity at the trans-Golgi network (TGN) in yeast and plays essential roles in protein transport in the secretory and endocytic pathways. ARF-like protein, Arl1p, is also known to regulate multiple membrane trafficking pathways. Our recent study demonstrated that Arl1p acts with an Arf-GEF, Gea2p, to modulate Drs2p activity at the TGN. We also reported that the golgin Imh1p, an Arl1p effector, forms the heterotetramer with Arl1p to attenuate GTPase-activating protein (GAP) Gcs1p activity toward Arl1p. Unexpectedly, we observed that the Arl1p still localize at the TGN in drs2-null cells, although the drs2-null exhibits severe defects in recruitment of Imh1p to the Golgi. The mechanism of Drs2p in modulating GTP hydrolysis is unknown. In this study, we demonstrate that Drs2p mediates Arl1p GTP-hydrolysis by interfere the ability of Gcs1p to access Arl1p. We first show that Arl1p remains in GTP-bound state in drs2-null cells. Expressing Gcs1p enhances the Arl1p GTP-hydrolysis in wild-type cells, but not in drs2-null cells. We also observed that lack of Drs2p impairs the Gcs1p to localize to the TGN. Thus, we infer that Drs2p modulates Arl1p GTP-bound state at the TGN through regulating the membrane curvature, which attenuates Gcs1p toward Arl1p. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/60839 |
全文授權: | 有償授權 |
顯示於系所單位: | 分子醫學研究所 |
文件中的檔案:
檔案 | 大小 | 格式 | |
---|---|---|---|
ntu-102-1.pdf 目前未授權公開取用 | 2.42 MB | Adobe PDF |
系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。